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  • Dr. Trish Pearce

4. What is a Circadian Rhythm?

A circadian rhythm is defined as any biological process that automatically sets itself on a 24 hour cycle. Many living things have some type of circadian rhythm, including humans, who use it to time our wake-sleep cycles. Two main hormones are involved (one of which will sound familiar): -Cortisol: A stress hormone produced by our adrenal glands, one of the main jobs of cortisol is to send a signal telling the body to release sugar (glucose) into the blood stream. THIS GIVES US ENERGY! -Melatonin: Produced by the pineal gland which is located in the brain, melatonin is produced in response to darkness and is responsible for giving us quality, restful sleep.

In a normal “cortisol/melatonin curve,” the two hormones oppose each other, with cortisol being at its highest upon waking and lowest at bedtime, and melatonin being lowest upon waking and highest at bedtime. Basically, this creates a graph that looks like this:

As you can see, when production of cortisol and melatonin are normal, they have a nearly inverse relationship, which allows us to have energy during the day and sleep restfully at night. But what happens when this normal rhythm becomes disrupted due to adrenal dysfunction?

The first graph is representative of stage II of adrenal maladaptation, or “resistance.” In this common scenario, the cortisol and melatonin curves have effectively been reversed, with cortisol at its lowest upon waking, and peaking just before bed. This is the classic picture of someone who is “wired and tired.” This person is someone who drags themselves through the morning and naps often, but is wide awake before bed and suffers from insomnia. The second graph is representative of stage III of adrenal maladaptation, or “exhaustion.” Neither curve has any appearance of being normal, and they both lack a “peak time,” and appear flat. This person’s overall levels of cortisol are far too low, because they have been in a state of adrenal dysfunction for so long they have lost the functional ability to produce enough cortisol. This person is someone who experiences debilitating fatigue almost all of the time, as well as symptoms of systemic inflammation, like overall weakness, joint and muscle pain, brain fog, and increased susceptibility to infection.

In the next article, we will discuss how to reset your circadian rhythm using simple lifestyle interventions like diet, exercise, and light/dark cycles.

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